One type of this sort of grinding apparatus has heretofore been known in which an upper support frame which extends horizontally in the lateral direction of the apparatus is stretched between and supported by supports of a frame in such a manner that the upper support frame is movable in the longitudinal direction, and a moving member is supported on the upper support frame so as to be laterally movable, and further a wheel head is vertically movably supported on the moving member.
In this grinding apparatus, however, the upper support frame is moved on the supports together with the moving member and the wheel head in order to change the position of the wheel head in the longitudinal direction. Therefore, it is necessary to provide guide support frames or the like for the upper support frame on both lateral sides, respectively, of the frame, and this complicates the structure. Moreover, the left and right sides of the frame are closed by the guide support frames or the like. Accordingly, there is the problem that it is considerably troublesome to handle a workpiece when it is loaded into or unloaded from the frame. In addition, to grind a processed surface of a molding die or the like which has a complicated configuration, it is generally necessary to press a grindstone against the processed surface and move the grindstone in this state so as to follow changes in configuration of the processed surface.
There has been known another type of the above-described sort of grinding apparatus in which a mounting member is vertically movably supported with respect to a moving member which is supported on a frame in such a manner that the moving member is movable in two directions which intersect each other at right angles within a horizontal plane, and a wheel head is vertically movably attached to the mounting member.
However, in grinding of vertically extending processed surfaces by the use of this grinding apparatus, when, after one surface has been ground, another surface is to be ground, it is necessary to change the direction or angle in or at which the grindstone is mounted to the wheel head. Particularly, in the case where the vertically extending surfaces are curvedly contiguous with each other, the operator must frequently and repeatedly change the grindstone mounting direction or angle, which results disadvantageously in a considerable lowering in the operating efficiency.
Further, in this grinding apparatus, the change of the position of the wheel head in the vertical direction can be effected only in the vicinity of the wheel head. Accordingly, the amount of change in the position is limited and it is therefore impossible to cope with a large workpiece, disadvantageously.
A still another type of the above-described sort of grinding apparatus has heretofore been known in which a mounting member is vertically movably supported with respect to a moving member which is supported on a frame in such a manner that the moving member is movable in the longitudinal and lateral directions, and a wheel head is supported with respect to the mounting member in such a manner as to be rotatable around an axis which extends horizontally in the lateral direction and also around an axis which extends longitudinally while intersecting said axis at right angles.
However, in this grinding apparatus, the wheel head is rotatably supported on the vertically movable mounting member, and the center of rotation of the wheel head is moved in accordance with the vertical movement of the mounting member. Accordingly, the distance from the wheel head to the center of rotation thereof is constant at all times. As a result, the movable range of the wheel head is limited by the angle of rotation thereof to a narrow range, which means that the grindstone cannot reach the innermost portion of the workpiece, disadvantageously.
In still another type of the above-described sort of grinding apparatus, a single grindstone is reciprocatively oscillated along a processed surface of a workpiece to grind it.
In this grinding apparatus, however, it is necessary to set a large oscillation stroke for the grindstone in order to enable a single grindstone to grind the processed surface over a wide range. However, such an arrangement leads to an increase in the moment of oscillation of the grindstone, resulting in the grindstone support mechanism portion being heavily loaded. Accordingly, it is necessary in this grinding apparatus to strongly build the grindstone support mechanism portion, so that the arrangement of the wheel head is complicated and increased in size, disadvantageously.
In still another type of the above-described sort of grinding apparatus, an abrasive member which is defined by a grindstone is pressed against a workpiece and this grinding member is rotated or oscillated sideward within one plane which is substantially parallel to the surface of the workpiece which is being ground, thereby effecting, for example, abrasive finishing of the surface of the workpiece.
In the above described grinding apparatus, however, the abrasive member only slides on the surface being ground. Therefore, the surface being ground is subjected to no cavitation nor striking action caused on the basis of the vertical oscillation of the abrasive member. For this reason, cuttings generated and accumulated in the area between the abrasive member and the workpiece during grinding are not effectively discharged. Accordingly, it is difficult to improve the grinding efficiency of the grinding apparatus, disadvantageously.
In still another type of the above-described sort of grinding apparatus, a grindstone is tiltably supported with respect to a moving member for reciprocatively moving it so that the abrasive surface of the grindstone extends parallel with the processed surface of a workpiece at all times.
However, in this grindstone tiltably supporting arrangement, when the grindstone is rotated around an axis which is orthogonal with respect to its abrasive surface, particularly when a grindstone whose abrasive surface is polygonal, e.g., quadrangular is used, a corner of the abrasive surface is located forward in the direction of movement as the grindstone is rotated. As a result, the corner may locally contact the processed surface of the workpiece, causing a large resistance to act against the movement of the grindstone, and thus hindering the movement.
In still another type of the above described sort of grinding apparatus, an air motor for activating a grindstone is rigidly fastened to a wheel head by means of nuts and bolts through an air motor mounting member.
For this reason, if, in the above-described grinding apparatus, the nuts are not sufficiently tightened, the air motor mounting angle may be deviated from a set mounting angle by the action of vibrations or grinding pressure generated during an operation, so that the air motor cannot be maintained at the set mounting angle, disadvantageously.
In still another type of the above-described sort of grinding apparatus, when a grinding path is to be stored in memory by moving a grindstone in a desired direction in advance, the movement of the grindstone is controlled from a position which is remote therefrom using a remote-controllable teaching device.
However, the arrangement that utilizes the teaching device has the problem that, since the teaching device is remote from the grindstone and they are not combined together in one unit, the operability is inferior and it is difficult to handle the apparatus, disadvantageously.
In still another type of the above-described sort of grinding apparatus, a nozzle is disposed in the vicinity of an abrasive member, and a grinding fluid is supplied from the nozzle to cool the frictional heat generated between the abrasive member and the workpiece.
However, it is necessary in a workpiece grinding apparatus to move the abrasive member in various directions as desired in accordance with a variety of configurations of workpieces. Accordingly, in the above-described grinding apparatus, the nozzle interferes with the abrasive member and limits the movement of the latter and the provision of the nozzle increases the number of required parts of the grinding apparatus, disadvantageously.
There is one type of grinding tool which is disclosed in Japanese Utility Model Publication No. 37-20287 (20287/1962). This tool is arranged such that a spherical joint receiver is fitted to a power transmission member which is secured to the distal end of a driving shaft, and projections are provided on the inner peripheral wall of a spherical hole provided in the spherical joint receiver in such a manner that the projections are equally spaced apart from each other along the circumference. On the other hand, a spherical portion of a spherical joint which is provided with a longitudinal slide groove engageable with the projections irremovably received within the spherical hole. In addition, a pad plate which is provided with sand paper is rigidly secured to the lower end of a leg portion of the spherical joint by means of a flat countersunk head screw. Further, a pressing spring is interposed between the pad plate and the above-described power transmission member so that a grinding operation can readily be carried out in accordance with irregularities on the processed surface without changing the angle of inclination of the driving shaft.
In the above-described grinding tool, the pressing force applied to the processed surface by the grinding apparatus acts on the spherical joint at the inner top portion of the spherical hole in the spherical joint receiver which is spaced apart from the sand paper. Accordingly, when the central axis of the pad plate intersects the central axis of the driving shaft at an angle as the pad plate follows irregularities on the processed surface, since the distance from the top portion of the spherical joint to the sand paper is long, the pad plate readily comes off the processed surface, undesirably. Therefore, in order to prevent the pad plate from coming off the processed surface, the pressing spring is provided to bias the pad plate, and the diameter of the pad plate is made much larger than the distance from the top portion of the spherical joint to the sand paper.
For this reason, the above-described grinding tool suffers from the following problems: the number of required parts is disadvantageously large; the structure is complicated; and much labor and time are needed to assemble the tool. In addition, since it is difficult to reduce the diameter of the pad plate to a substantial extent, it is disadvantageously impossible to grind irregularities having small curvatures.
As one type of this sort of grinding tool, for example, a grinding tool such as that shown in FIG. 85 is known in which a grindstone 2231 is rigidly secured to the distal end of a base member 2230 which is inserted into a recess 183 in a workpiece 101. The base member 2230 is connected to an oscillation generator for a wheel head in a grinding apparatus (these are not shown), and after one inner wall surface 181 has been ground by the oscillation of the grindstone 2231 under pressure, the grindstone 2231 is turned upside down to grind the other inner wall surface 182.
In the case of using this grinding tool, however, an independent grinding step is needed for each processed surface and, in addition, every time processed surfaces to be ground are changed from one to another, the grinding tool must inconveniently be dismounted from and remounted on the wheel head, and this lowers the operating efficiency. When the recess 183 is narrow, the pressure with which the grindstone 2231 is pressed against the processed surface may be nonuniform, that is, said pressure at the inner end side of the recess 183 may be different from that at the open end side, resulting in unevenness of grinding. Further, when the recess 183 is narrow, it may be impossible to insert the grinding tool itself into the recess 183.
It is an object of the present invention to provide a grinding apparatus which facilitates handling of a workpiece including loading thereof and unloading thereof after machining.
It is another object of the present invention to provide a grinding apparatus which is capable of readily coping with a variety of workpieces which have various sizes.
It is still another object of the present invention to provide a grinding apparatus which enables a grindstone to reach satisfactorily the innermost portion of a processed surface of a workpiece.
It is a further object of the present invention to provide a grinding apparatus which is capable of successively grinding processed surfaces of a workpiece.
It is a still further object of the present invention to provide a grinding apparatus which is capable of efficiently grinding a processed surface.
It is a still further object of the present invention to provide a grinding apparatus and method which enables a pressure cylinder to be readily switched over between an operative state and an inoperative state.
It is a still further object of the present invention to provide a grinding apparatus and method which enables data concerning a grinding path to be readily stored in memory.
It is a still further object of the present invention to provide a grinding apparatus and method which enables a grinding operation to be efficiently carried out without the need to designate a grinding path for each machining process.
It is a still further object of the present invention to provide a grinding method which has no need to move a wheel head from a movement terminating position to a movement starting position after the completion of the teaching step and therefore enables the operation to be simplified.
It is a still further object of the present invention to provide a grinding apparatus and method which involves no fear of a grindstone to collide with a projection or the like on the processed surface.
It is a still further object of the present invention to provide a grinding apparatus and method which enables a grinding operation to be safely carried out without any fear of a grinding operation or the like being continued with a grindstone being overloaded and without any risk of a grinding operation to be repeatedly conducted on the basis of erroneous grinding path data.
It is a still further object of the present invention to provide a grinding apparatus which is capable of grinding a processed surface uniformly and with high accuracy without any unevenness of grinding, i.e., without any fear of a recess in the processed surface being insufficiently ground and without any fear of a projection on the processed surface being excessively ground.
It is a still further object of the present invention to provide a grinding apparatus which is capable of minimizing vibration of the grindstone which are transmitted to the frame.
It is a still further object of the present invention to provide a grinding apparatus which enables even a narrow portion in a processed surface having a complicated configuration to be readily ground.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that it is possible to simplify the arrangement of each moving member and the frame.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that the performance of the grindstone to follow the processed surface is improved in order to enable a grinding operation to be carried out without any hindrance.
It is a still further object of the present invention to provide a grinding apparatus which is capable of uniformly grinding a processed surface by enabling the grindstone to readily follow even irregularities on the processed surface which have small curvatures.
It is a still further object of the present invention to provide a grinding apparatus which is free from a fear of the air cylinder and the rotary mechanism portion interfering with each other in response to the rotation of the wheel head.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that it is possible to eliminate the need for the operator to change the position of the grindstone in which it is mounted on the wheel head in accordance with the position of the processed surface to be ground, thereby enabling an improvement in the operating efficiency.
It is a still further object of the present invention to provide a grinding apparatus and method which is so designed that, when the grindstone moves along an erroneous path during the teaching step, the teaching step need not be redone from the beginning, and there is no fear of the machining time being wasted in the playback step and no fear of the erroneous path portion being unevenly ground by overgrinding.
It is a still further object of the present invention to provide a grinding apparatus and method which enables the teaching step to be carried out continuously and smoothly.
It is a still further object of the present invention to provide a grinding apparatus and method which enables an operation for correction to be simply and speedily carried out in the teaching step.
It is a still further object of the present invention to provide a teaching box used in a teaching operation in relation to a grinding apparatus or the like, the teaching box being so designed that accurate teaching can be effected with a simple structure and there is substantially no fear of failure.
It is a still further object of the present invention to provide a grinding apparatus wherein the grindstone is smoothly reciprocated to enable a grinding operation to be carried out smoothly.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that there is no need to increase the grindstone operating stroke and it is possible to simplify the arrangement of the wheel head and reduce the size thereof as well as enable a processed surface of a workpiece to be ground over a wide range at the same time by cooperation of a plurality of grindstones.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that a plurality of grindstones can be driven by means of a single common motor and it is therefore possible to simplify the arrangement for driving the same.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that a workpiece is eroded by means of cavitation and striking action caused on the basis of vertical vibration of an abrasive member in addition to grinding effected by the reciprocative movement of the abrasive member within a horizontal plane and cuttings which are generated from the grinding member and the workpiece are discharged without any fear of residing in the area therebetween.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that an abrasive member can be brought into contact with a ground surface of a workpiece over a wide area.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that there is no need to dispose an obstructive member such as a nozzle for supplying a grinding fluid in the vicinity of an abrasive member, thereby enabling an increase in the degree of freedom with which the abrasive member moves and also permitting a reduction in the number of required parts.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that it is possible to increase the workpiece cooling effect by means of a grinding fluid.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that the grindstone is not rotated around an axis which intersects its abrasive surface at right angles.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that the grindstone can smoothly be moved without any hindrance With its abrasive surface being kept parallel with the processed surface of a workpiece.
It is a still further object of the present invention to provide a grinding apparatus which exhibits excellent operability in the teaching step and which can be handled extremely easily.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that it is possible to clearly designate the direction in which an actuating member may be operated with a reduced number of indicating elements and to thereby improve the operability.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that it is possible to readily adjust the angle at which the wheel head is mounted with respect to the Z-direction moving shaft.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that an air motor can be readily and reliably retained in a position of desired angle.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that it is possible to readily and accurately adjust the amount of air to be supplied to each of the first and second air cylinders.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that the grindstone can readily be inserted into and removed from a recess in a workpiece.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that it is possible to simultaneously grind a plurality of inner wall surfaces of a workpiece in a single step without the need to change the position of the grindstone. It is a still further object of the present invention to provide a grinding apparatus which is so designed that, when a ribbed workpiece which has a plurality of grinding blocks is to be ground, it is possible to reduce the number of times of movement of the grindstone along non-grinding paths corresponding to the ribs of the workpiece, so that it is possible to eliminate a waste of time and to thereby enable the machining efficiency to be further improved.
It is a still further object of the present invention to provide a grinding apparatus which is so designed that the processed surface of a workpiece can be finished beautifully without any fear of a pattern of movement of the grindstone being left on the finished surface.